Bulk delete contacts #149

You can only delete one contact at a time (DELETE /contacts/:contactId, the delete_contact MCP tool, and the contacts page). Cleaning a list after an import, or handling an erasure request across many records, needs bulk delete. Every major platform (Mailchimp, Klaviyo, ActiveCampaign) has it.

Scope

• API: bulk delete by an explicit list of ids and by filter/segment, run as a background job for large sets with a count preview first. Update the OpenAPI docs.
• Semantics: deleting a contact cascades its email_deliveries and custom field values. Keep the suppression entry (by address) so a deleted, unsubscribed contact can't be re-imported and mailed. Document whether delete means a GDPR erasure.
• MCP: add a delete_contacts (bulk) tool.
• Dashboard: row selection on the contacts table, plus "Delete N contacts" with a typed confirmation for large counts.